Welcome to the forum.
Questions 1-3: The exposures you describe carry no risk for any STD. If a bare penis (no condom) is not inserted into another person's vagina, rectum, or mouth, no STDs are transmissible.
Question 4: It is exceedingly unlikely you acquired anything by oral sex that would persist 5 years. For sure chlamydia and gonorrhea cannot do that, and if you had no penile sores/blisters in the few weeks following the events, you can be very confident you did not catch herpes or syphilis. And HPV/warts are not transmitted by oral sex.
I hope this helps. I notice you posted the same question on the international forum. We (and they) recommend against asking the same question on both forums. Our opinions and advice are virtually never different; you can expect their advice to be more or less identical to mine. It's too late now, but perhaps other users will save their excess posting fees.
Regards-- HHH, MD
Many thanks Doctor Handsfield for the reassurance, I really appreciate it.